package com.zhuxiang.util;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class PasswordEncoder {
    private static final String hexDigits[] = {"0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};
    private Object salt;
    private String algorithm;
    public PasswordEncoder(Object salt,String algorithm){
        this.salt = salt;
        this.algorithm = algorithm;
    }
    public String encode(String rawPass){
        String result = null;
        try {
            MessageDigest md = MessageDigest.getInstance(algorithm);
            result = byteArrayToHexString(md.digest(mergePasswordAndSalt(rawPass).getBytes("utf-8")));
        } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return result;
    }

    private String mergePasswordAndSalt(String password) {
        if (password == null){
            password = "";
        }
        if ((salt==null)||"".equals(salt)){
            return password;
        }else {
            return password+"{"+salt.toString()+"}";
        }
    }

    private static String byteArrayToHexString(byte b[]) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++)
            resultSb.append(byteToHexString(b[i]));

        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n += 256;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

}
